There must be some sort of wealth transfer in order to receive feedback.
Otherwise, I can let a bunch of people on my account to do a one level powerlevel (or even a 15xp powerlevel like a user admitted to doing already) and just fb farm like that.
This shouldn't be allowed at all. It can be greatly abused and more and more people are starting to do it. There should be a minimum of 1m traded in order to leave feedback. Buying/selling items for GP shouldn't result in feedback either unless it's on different platforms (RS3 items for 07 GP and vise versa) since that way there could be a risk of being scammed.
Currently, it's at 1m RS3 gp or 100k 07 gp for feedback, which is just ridiculous. It should be 1m 07 or 10m RS3.